1. Technical Field
The present invention relates to a back light module, and more particularly to a back light module with uniform light-emitting and a display device using the same.
2. Description of the Related Art
The liquid crystal display device is widely used in cellar phone, notebook, personal computer, personal digital assistant and other consumer electronic products. FIG. 1A is a schematic disassembling view of a conventional liquid crystal display device. FIG. 1B is a cross-sectional, schematic view of the liquid crystal display device of FIG. 1A. Referring to FIGS. 1A and 1B, the liquid crystal display device 100 includes a liquid crystal display panel 102 and a back light module 104, and the back light module 104 is located at one side of the liquid crystal display panel 102 for providing the enough brightness to the liquid crystal display panel 102 for displaying.
The back light module 102 includes a bezel 110, a reflector 120, a light-guide plate 130, an optical film 140 and a light source unit 150. The bezel 110 is composed of a plurality of frame strips 112, and the frame strips 112 surrounds an accommodating space 113. Each frame strip 112 has a carrier surface 111 and the display panel 102 is configured on the bezel 110 and contacts to the carrier surface 111. Moreover, the carrier surface 111 has at least one cave 115. The reflector 120 and the light-guide plate 130 are sequentially configured in the accommodating space 113. The optical film 140 is configured on the light-guide plate 130. Further, the optical film 140 has at least one protrusion 142 corresponding to the cave 115 of the frame strip 112 of the bezel 110, and the depth H of the cave 115 is consistent with the thickness T of the protrusion 142 of the optical film 140, so that the protrusion 142 can be located within the cave 115 for temporarily positioning the optical film 140. The light source unit 150 is configured at the light-incident side 132 of the light-guide plate 130 to providing a light to the liquid crystal display panel 102 for displaying images.
However, since the general optical film 140 includes prism film 144 and diffusion film 146 with condensing function, when the light emitted from the light source unit 150 is reflected by the frame strip 112 to the diffusion film 146, several bright lines will resulted therein around the diffusion film 146. Therefore, the uniformity of light-emitting of the back light module 104 would be decreased.
In order to solve the above-mentioned issue, a light-shielding band 160 is configured around the diffusion film 146 to prevent from forming the bright lines around the diffusion film 146 and increase the uniformity of light-emitting of the back light module 104.
However, as shown in FIG. 1B, after the light L emitted from the light source unit 150 emits into the cave 115 of the frame strip 112, the light L will be repeatedly reflected between the frame strip 112 and the light-shielding band 160 and through the prism film 144 several times in the cave 115, therefore the light will be condensed in the cave 115 so as to decrease the uniformity of light-emitting at the protrusion 142.